1. Field of the Invention
The present invention relates to golf balls. More particularly, the present invention relates to multi-piece golf balls having a center, a mid layer and a cover.
2. Description of the Related Art
Golf balls make a flight with accompanying back spin. Top concern to golf players for golf balls is their flight performances. The flight performance correlates with back spin rate. The flight with small spin rate results in an appropriate trajectory, whereby a great flight distance can be achieved. In light of the flight performance, golf balls which are less likely to be spun have been demanded.
Golf balls hit with an ideal swing are not accompanied by side spin. However, the side spin is inevitable according to common swings. Golf players expect golf balls that are excellent in the directional stability. The golf balls follow a curved trajectory owing to the side spin. Also in light of the directional stability, golf balls that are less likely to be spun have been desired.
The golf players place great importance also on feel at impact of the golf balls. Golf players prefer soft feel at impact.
Japanese Unexamined Patent Application Publication No. Hei 7-24085 (U.S. Pat. No. 5,553,852) discloses a golf ball having a center, a mid layer and a cover. The specific gravity of this mid layer is smaller than the specific gravity of the center. In this type of golf ball, the mass distribution has a disproportionate pattern indicating greater weighing in the inner part. This golf ball will generate excessive spin.
Japanese Unexamined Patent Application Publication No. Hei 9-313643 (U.S. Pat. No. 5,830,085) discloses a golf ball having a core, a mid layer and a cover. The hardness of this mid layer is greater than the surface hardness of the core. This mid layer may deteriorate the feel at impact of the golf ball.
Japanese Unexamined Patent Application Publication No. Hei 11-253578 (U.S. Pat. No. 6,129,640) discloses a golf ball having a core, a mid layer and a cover. This mid layer includes polyurethane as a principal component. Such a mid layer may deteriorate the resilience performance of the golf ball. This golf ball is inferior in the flight performances.
Japanese Unexamined Patent Application Publication No. 2006-289059 (US2006/211517) discloses a golf ball having a core, a mid layer, a reinforcing layer and a cover. In this type of golf ball, the mass distribution has a disproportionate pattern indicating greater weighing in the inner part. This golf ball will generate excessive spin.
Japanese Unexamined Patent Application Publication No. 2006-289060 (US2006/211517) discloses a golf ball having a core, a mid layer, a reinforcing layer and a cover. In this type of golf ball, the mass distribution has a disproportionate pattern indicating greater weighing in the inner part. This golf ball will generate excessive spin.
Requirements for golf balls by golf players have been increasingly escalated. An object of the present invention is to provide a golf ball that is excellent in the flight performance, directional stability and feel at impact.